Systems for the thermal product treatment of beverages usually have a capacity of about 1,000-5,000 liters. Experience shows that a product quantity at least corresponding to the capacity of the treatment system is required for a successful product treatment. For example, residual amounts at the end of a production batch which are smaller than the capacity of the treatment system cannot be processed. It is neither possible to treat a batch that is smaller than the capacity of the treatment system. However, it would be desirable to be able to utilize as much as possible of the product to be treated.
Moreover, during a medium change on the inlet side, for example when the product to be treated has completely flown into the treatment system and the product still present in the treatment system is expelled with water, it is common to switch the product outlet depending on the state. Thus, in the worst case, a product quantity corresponding to the capacity of the treatment system is lost at the end of the treatment. Therefore, there is a demand to reduce product loss during a medium change.
Moreover, a product return pipe which is provided for circulating the product in case of a standstill of a downstream production unit is usually filled already at the beginning of the treatment before the treated product is forwarded for intermediate storage. However, this requires that the product return pipe is also filled in case of a trouble-free operation of the downstream production system, although this would not be necessary with respect to production. The treated product led into the product return pipe must then be rejected after treatment. It would be desirable to minimize this product loss, too.
Another problem with the medium change in a thermal product treatment system arises in systems in which a degassing apparatus is integrated. During a medium change, the product flow at the degassing apparatus is usually interrupted, so that the medium present in a heat exchanger upstream of the degassing apparatus will dwell therein for an undesired long time and will be excessively heated. This will impair product quality. Moreover, the degassing apparatus must be subsequently refilled at a highly increased flow rate, resulting in a reduced thermal absorption of the medium passed through it, which in turn can have a negative influence on product quality, for example due to a reduced effectiveness of degassing.
Therefore, there is a demand for a method and a device by means of which the above mentioned problems can be moderated or even eliminated.